The invention discloses a wind turbine generator blade bonding corner and further discloses a preparation method of the wind turbine generator blade bonding corner. The wind turbine generator blade bonding corner is provided with lining plates and a U-shaped structure. The outer side shape of the U-shaped structure is matched with the inner side shape of a corresponding blade bonding area, and thelining plates are arranged along the inner side of one edge or two adjacent edges of the U-shaped structure. The preparation method comprises the steps that (1) the lining plates are prepared insidethe parting line of one face of a blade shell according to the shell inner wall shape, and the lining plates are subjected to demolding and edge trimming; and (2) a bonding corner laying layer is manufactured through a fiber cloth and resin, then the parting line side of the prepared lining plates is aligned at the center line of the bonding corner laying layer to place the bonding corner laying layer and the lining plates between a bonding corner mold and the blade shell, the lining plates are clamped on the bonding corner mold through a clamp, after the bonding corner laying layer is solidified, demolding is conducted, and then the bonding corner with the lining plates is obtained. The following property of the bonding corner with the lining plates and the shell is high, the defects thatan existing bonding corner is corrugated and deformed, and positioning is poor can be overcome, and the blade bonding quality is improved.